kush wrote:
It's been quite a few years since that chemistry class I never took, so if
someone could give me a hand here, I'd be grateful.
I've got a 75-gallon standard tank with 110 watts of lighting.
This is low for a plant tank, but acceptable as long as you don't inject CO2.
The tank has
lots of wood in it and is moderately to heavily planted and I'm injecting
CO2 through a powerhead and also with a diffuser next to the filter output.
Oops! High CO2 plus low light. This is an imbalance which often causes algae
soup.
I have a pretty heavy fish load for a planted tank, but my maintenance is
impeccable (imho).
Ph.............7.4-7.5
Nitrate.......not measurable
Nitrite........ 0.5 ppm
Gh.............3º
Kh............. 12º
Fe............. not measurable
I say the carbonate hardness is not measurable because after 12 drops it
just turns the same colour as the test liquid.
A bit of confusion perhaps...
Nitrate with an A is the end result of the nitrification cycle. It is extremely
unlikely that it is unmeasurable in a heavy fish load tank, although
measurements under 5ppm are common when the tank is also heavily planted.
Nitrite with an I is an intermediate product of the nitrification cycle. In a
mature tank, it goes to zero and stays there forever. It is also toxic to fish.
Is it possible you have reversed these measurements?
In any case, Plants cannot grow without Nitrate with an A, as it is an important
macronutrient. Given that you are dosing micronutrients such as Fe, you are
probably creating a substantial imbalance.
Regarding your KH and pH, these are probably not your problem, although it would
be interesting to know where all that KH is coming from. What kind of substrate
and stone is in the tank?
Recommendations: Your light level is too low for a CO2 tank. Either stop
injecting CO2 or double your lighting.
Untangle your test results to figure out actual levels of Nitrate with an A and
Nitrite with an I. If Nitrate is actually unmeasureable, you will have to dose
KNO3 to allow plant growth.
These links are all from the group FAQ:
Background on water hardness:
http://faq.thekrib.com/begin-chem.html
Lighting:
http://www.thekrib.com/Lights/
http://faq.thekrib.com/plant-lighting.html
Nitrate and test kits:
http://faq.thekrib.com/begin-tests.html